package training.day05;//将两个升序链表合并为一个新的 升序 链表并返回。新链表是通过拼接给定的两个链表的所有节点组成的。
//
//
//
// 示例 1：
//
//
//输入：l1 = [1,2,4], l2 = [1,3,4]
//输出：[1,1,2,3,4,4]
//
//
// 示例 2：
//
//
//输入：l1 = [], l2 = []
//输出：[]
//
//
// 示例 3：
//
//
//输入：l1 = [], l2 = [0]
//输出：[0]
//
//
//
//
// 提示：
//
//
// 两个链表的节点数目范围是 [0, 50]
// -100 <= Node.val <= 100
// l1 和 l2 均按 非递减顺序 排列
//
// Related Topics 递归 链表
// 👍 1829 👎 0


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/**
 * Definition for singly-linked list.
 * public class ListNode {
 * int val;
 * ListNode next;
 * ListNode() {}
 * ListNode(int val) { this.val = val; }
 * ListNode(int val, ListNode next) { this.val = val; this.next = next; }
 * }
 */
public class L21 {

    public static void main(String[] args) {
        ListNode listNode1 = new ListNode(1, new ListNode(2, new ListNode(4)));
        ListNode listNode2 = new ListNode(1, new ListNode(3, new ListNode(4)));
        ListNode listNode = mergeTwoLists(listNode1, listNode2);
        System.out.println();
    }

    public static ListNode mergeTwoLists(ListNode l1, ListNode l2) {
        if (l1 == null) {
            return l2;
        } else if (l2 == null) {
            return l1;
        }
        ListNode t1 = l1;
        ListNode t2 = l2;
        ListNode startNode = l1.val > l2.val ? l2 : l1;
        ListNode lastNode = new ListNode();

        while (t1 != null && t2 != null) {
            if (t1.val > t2.val) {
                //t2进入
                lastNode.next = t2;
                lastNode = t2;
                t2 = t2.next;
            }else {
                lastNode.next = t1;
                lastNode = t1;
                t1 = t1.next;
            }
        }
        lastNode.next = t1 == null ? t2 : t1;
        return startNode;
    }

    public static class ListNode {
        int val;
        ListNode next;

        ListNode() {
        }

        ListNode(int val) {
            this.val = val;
        }

        ListNode(int val, ListNode next) {
            this.val = val;
            this.next = next;
        }
    }
}
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